Re: Database design

From: Alexandr Savinov <spam_at_conceptoriented.com>
Date: Thu, 23 Feb 2006 09:43:59 +0100
Message-ID: <43fd75ce$1@news.fhg.de>

x schrieb:
> "Alexandr Savinov" <spam_at_conceptoriented.com> wrote in message
> news:43fc6eec$1_at_news.fhg.de...

>> x schrieb:

>>> Do you know about any published academic paper about relational

> databases in

>>> which the term flat is defined  ?
>>> Why is it useful to define this term from a scientific point of view ?
>> There is several reasons why it is useful:

>> 1. It allows us to get an informal impression and what is the essence,
>> what we are talking about. An informal characterization (an idea) is the
>> primary thing while formalities is the secondary thing (a tool which
>> makes it easier to derive consequences).

>
> Ok.
>

>> 2. Just because we use other informal terms in order to describe a
>> theory or approach. Eventually, in any academic paper and in this group
>> most of words have no formal definition. And this does not prevent us to
>> comprehend them. And again: writing formulas does not add a value to any
>> theory - it is only a form which may make it easer or more difficult to
>> understand.

>
> You mentioned other "exotic" terms from science (Fuzziness and roughness of
> sets, charmness of quarks )
> Fuzziness of sets has a precise definition.
>

>> 3. This group is intended to discuss what is not covered by academic
>> papers so there is nothing bad that we can introduce something unusual.

>
> I don't know for what is intended.
>

>> Anyway, I do not understand why a structure without an order (hierarchy,
>> multiple levels, depth etc.) cannot be characterized as flat? It is
>> rather precise characterization (in contrast to many terms from academic
>> papers which are frequently simply misleading).

>
> third level - the relation
> second level - the tuple
> first level - the value
> And each value belong to a domain also.
>
> How flat is this.

Because what you wrote is actually a definition of being flat:

Space (say, 2-dimensional Euclidean space) Point (in this space, as a combination of 2 coordinates) Coordinate (a projection of the point on some axis)

Since there is no continuation (this space is not nested) we say it is flat. We can build a non-flat space if assume that coordinates are themselves points with their own coordinates. Those coordinates could also be points with their own coordinates and so on. Alternatively, we can continue this space hierarchy in the opposite direction (upward). The points from this set can be used as coordinates for points from another set. Those points can again be used as coordinates.

So we call a structure flat if it can be shown equivalent to a n-dimensional space (without a hierarchy).

-- 
http://conceptoriented.com

Received on Thu Feb 23 2006 - 02:43:59 CST